Ask questions, meet dancers, and be part of the conversation.
It adds opportunities for new moves, like when Serkhan climbs on Ozhan's leg. A straight couple would have difficulties to emulate this because of the pointy heel of the lady.
I'd probably say traditional rather than straight. They don't really give any indication of their personal orientation. There's at least one all women tango group here in the US and I would call them gay.